What is an ORCHID?
The Orchid is one of mother earths’ most beautiful, magnificent and magical flower which grows on the edge of a slender stalk of the plant. The orchid consists of three inner petals, three outer petals, and a cupped shaped petal, which is distinct from the rest and gives an altogether out of the world look to the flower. Yes, it is exotic, delicate and once seen will always create in you a desire to possess. Its’ sweet scent is so scintillating that if you are very near to it you would never miss it.
The orchids have survived all these ages, mainly because of the multi pollinating techniques adopted by the species. They multiply by pollination through the medium of bees, wind, crawling insects, small mammals and hummingbirds. World wise there are some 35,000 species of the orchid. It thrives best in the rainforests. However it can be seen in the Alpine and the Himalaya range of mountains. Majority of the cultivated orchids are native of tropical countries and occur in their greatest diversity in humid tropical forest of South and Central America, Mexico, India, Ceylon, Burma, South China, Thailand, Malaysia, Philippines, New Guinea and Australia. Brazilian cattleyas, Mexican laelias and Indian dendrobiums, cymbidiums and vandas have played a major role in the development of modern orchid industry in the world.
It is estimated that about 1,300 species of orchids are found in our country with Himalayas as their main home and others scattered in Eastern and Western Ghats.
The following is the distribution of orchid’s species in different regions of India.
North-Western Himalayas 200 species
North-Eastern India 800 species
Western Ghats 300 species
Some of the Indian orchid species which are of high ornamental value are:
Aerides crispum, A. fieldingii, A. multiflorum, A. odoratum, Anaectochilus roxburghii , Arachnis clarkei, Arundina graminifolio, Bulbophyllum leopardinum, Calanthe masuca, Coelogyne elatn, C. devonianum, Cymbidium pendulum, C. longifolium, C. munronianum, Dendrobium aggregatum, D. aphyllum, D. fimbriatum, D. jenkinsii, D. moschatum, D. nobile, Paphiopedilum faireanum, P. venstum, P. hirsutissium, p. insigne, Phaius wallichii, Pleione praecox, Rhynchostylis retusa, Thunia alba, Vanda cristata, V. coerulea and V. coerulescens.
Majority of the cultivated orchids are native of tropical climates and are found in abundance in India in the state of Assam, Meghalaya, West Bengal, Karnataka and Kerala. Kalimpong, Shillong, Trivandrum, Bangalore, Yercaud.
Orchids can be divide into two groups - monopodial or sympodial depending upon their habit of growth.
Orchids known as epiphytic orchids normally grow on the bark of the trees. We also have grounds orchids or terrestrial orchids which grow like ordinary plants with their roots in soil. Most of the temperate zone orchids are terrestrial and tropical orchids are epiphytes. Orchids in nature grow protected from the tropical sun by the shades of trees. Under controlled condition the orchids can be grown in specially designed orchidaria or orchid houses, running North and South and made from materials like split bamboo, glass, shade nets, etc.
There are also orchids which can be grown in open sun. Various leave species of Vanda, Aranda, Arachnis, Renanthera, kegawara, Mokara etc. can be grown in open trenches filled with brick pieces, charcoal as is done in Ceylon, Singapore and Thailand.
Indirect sunlight is ideal for orchids. Seedlings require less light than adult plants. Very poor light tends to produce weak plants and retards flowering. A plant which has been grown in shades should gradually be shifted to sunlight conditions. The optimum requirement of light varies between species to species. Cypripedium and Phalaenopsis require only 200-300 watts Whereas Vanda and Aranda thrive best under 800 watts.
Orchids dislike sudden change in temperature, however a difference of 10-20 degree C between day and night temperatures is benificial for their growth. The best suitable range is 18 to 30 degree C, with proper ventilation, which provides fresh air and also helps in reducing the temperature.
WATERING & HUMIDITY
Humid warm atmosphere is most essential for the growth of most of the tropical orchids, which do not have well established root system. It is a good idea to have a water tank or pool in the center of the orchidaria to maintain humidity, which should not be less than 30% at night and 80% during day time, The plants should be watered 2-3 times a day and should not be allowed to dry up during hot climate. Plants in active growth require more water. Similarly plants in baskets require more water than those in pots. Care should be taken to water the plants with a fine spray by using standard nozzles and not to hit the plants with powerful jets of water. Plants which are freshly potted should be watered very sparingly till the new roots appear and watering should be gradually increased.
Orchids should be potted in small pots according to the size of the plants. As a thumb rule, orchids should be under potted to get more flowers. Any kind of pot which can hold medium and provide aeration is suitable. Most people prefer plastic pots which retain moisture longer than mud pots. Vandaceous and Sarcenthene orchids can be grown in teak-wood baskets. Orchid plants should not be disturbed frequently and repotting done only when absolutely necessary.
Orchids like Cymbidium, react favorably when repotted after 2-3 years whereas Vandeceous orchids and Paphiopedilum should not be disturbed unless very necessary.
Terrestrial orchids, like Spathoglottis, Phaius and Calanthe, should be grown in 20-25 cm pots with 1:1:1 mixture of leaf mould, FYM and sand. For Paphiopedilum A mixture of 2:2:1 of leaf mould, loam soil and brick pieces and charcoal is recommended.
Potting Mix Orchids have very different growing material needs from other plants like trees or vegetables. Instead of organic soils and composts, Orchids need an appropriate mix of water retaining and aerating materials. The ratio depends on the type of orchid.
The growing medium is always a combination of organic fibers and inorganic materials. Ready-mix mediums are convenient and easy to use and can be bought at just about any nursery or home center. You can also mix your own medium from a wide variety of materials. Each has advantages that are apparent with experimentation and experience.
Most materials used for mixes come in fine, medium, and coarse grades .
Organic choices include:
Fir Bark Easy to find, inexpensive, fairly slow to decompose though difficult to hold water.
Redwood Bark Holds water better than Fir Bark and decays more slowly ater initially.
Coconut Husks Among the first fibers to be used for orchids. Inexpensive, lightweight, holds water moderately well, but decays more quickly than fir bark.
Sphagnum Moss Produces a good balance of water and air retention. Do not pack tightly.
Tree Fern Fibre, drains well and decomposes slowly but difficult to obtain.
Charcoal Slow to decay and absorbs toxic substances. Lava rock Good Drainage and never breaks down. Can be heavy. Alifor Little clay pieces that provide moderate drainage. Decay proof.
Vermiculite Holds water thereby increasing aeration.
Pearlite Absorbs water, high decay resistance, very light. Use in combination with other Inorganic material. Used alone it holds too much water.
Turface used to replace pearlite. Heavy and expensive.
From these ingredients you can custom make an orchid potting mix that will work for your particular orchid. Check out the links below to read more about plant care of orchid, potting mixes for seedlings, and potting mix recipes.
Recipes for Potting Medium for Orchids:
In nature, orchids obtain their supply of inorganic nutrients like calcium, magnesium, iron, potassium, nitrogen and traces of manganese, boron, copper, zinc etc. from the tree on which they are growing and also from atmosphere and decaying vegetables and dropping of birds. However under controlled conditions they have to be supplied with all these major and minor nutrients. Taking into consideration the special need of different orchids, a large number of fertilizer mixtures, both solid and liquid, are available in market.
Liquid fertilizers are much more quickly absorbed and can be applied more frequently. As the orchids are slow growing, slow release fertilizers like osmocote can be used to get very good result. Usage of fertilizers should also depend on stage of growth. During vegetative growth, large quantities of nitrogen are required while during flowering, nitrogen should be reduced and amount of phosphate increased.
We have been getting excellent results by using slow release fertilizer mixtures (NPK
DISEASES & PESTS
Like all other plants orchids are also pone to a number of diseases caused by fungi, virus, bacteria, insects and pests. The most common diseases in each group are:
FUNGAL AND BACTERIAL DISEASES
Leaf spot - caused by Colletotrichum and Gleosporium
Leaf blight - caused by Pythium
Collar blocth - caused by Penicilium thomii
Collar rot - caused by Sclerotium
Orchid wilt - caused by Sclerotium rolfsli
Various fungicides like Captan, Dithane, Agrosan and Ceresan are very effective against these diseases.
More than 32 diseases are known to occur on orchids. In some cases the same virus has been known to produce more than one disease in different species, the most common are Cymbidium mosaic virus.
As control measures all infected plants should be isolated to prevent spreading of the disease.
The most commonly reported insects pests on orchids are thrips, aphids, spider mite, soft scale, mealy bugs, orchid weevil, snail and slugs. These insects’ pests harm the plants in many ways. They feed on tender young shoot, suck the sap and damage the young bud and shoots and also act as the carrier of different diseases.
Fortunately all these can be controlled by effective insecticides like Parathion, Malathion, BHC, CPC, Dieldrin, etc. Metaldehyde has proved to be very effective in killing slugs and snails.
Orchids like other Horticultural crops may be propagated as under:
Orchids like Aerides, Arachnis, Epidendrum, Renanthera, Phalaenopsis, Vanda and Dendrobium can be propagated by cutting. Orchids cutting are usually bigger and should possess one or more roots. Cutting are usually potted in propagation beds or directly in pots after treating the cut ends with fungicides to prevent rotting.
Cutting of genera, like Aerides, Arachnis, Vanda etc., are very hardy and can be directly potted in pots, whereas those of dendrobium and Phalaenopsis need special care to root and should be potted in propagation beds.
The propagation of orchids through cuttings is getting popular again and some of the nursery men like to propagate their orchids through cuttings to get uniform plants.
Most of the sympodial orchids, like Coelogyne, Cattleya, Dendrobium and Cymbidium, are propagated through this method. The method involved consists of dividing large clumps into smaller units. However care should be taken not to divide the plants unless there are 8-10 pseudo-bulbs. Dendrobiums which are very fast growing can be divided every year.
In some monopodial orchids like Ascocenda and Phalaenopsis, off-shoots emerge frequently on the main stem. This usually happens when the apex has lost its effectiveness in suppressing axillary buds.
Most of the dendrobiums produce aerial shoots or bulbs on old back bulbs devoid of leaves. They usually arise on the upper part of the back of the bulbs and grow slowly. These aerial shoots take 90-120 days to develop roots. At this stage, they are detached along with the portion of back of the bulb and potted as independent plant.
The Goodyera, Rhizomes gives off special lateral branches which turn up and produce aerial shoots. When they are properly rooted they get detached from the mother plant and establish separately.
Orchids can also be propagated through Seeds and Tissue Culture both of which are very highly technical in nature and take a very long time as such these methods cannot be adopted by the home Gardner.